chore: use preventDefault util (#4412)

src/number-keyboard/demo/index.vue

@@ -21,7 +21,7 @@
 
     <demo-block :title="$t('custom')">
       <van-button
-        type="primary"
+        type="info"
         @touchstart.stop="keyboard = 'custom'"
       >
         {{ $t('button2') }}

src/number-keyboard/test/__snapshots__/demo.spec.js.snap

@@ -10,7 +10,7 @@ exports[`renders demo correctly 1`] = `
       <div class="van-number-keyboard__body"><i role="button" tabindex="0" class="van-hairline van-key">1</i><i role="button" tabindex="0" class="van-hairline van-key">2</i><i role="button" tabindex="0" class="van-hairline van-key">3</i><i role="button" tabindex="0" class="van-hairline van-key">4</i><i role="button" tabindex="0" class="van-hairline van-key">5</i><i role="button" tabindex="0" class="van-hairline van-key">6</i><i role="button" tabindex="0" class="van-hairline van-key">7</i><i role="button" tabindex="0" class="van-hairline van-key">8</i><i role="button" tabindex="0" class="van-hairline van-key">9</i><i role="button" tabindex="0" class="van-hairline van-key van-key--gray">.</i><i role="button" tabindex="0" class="van-hairline van-key">0</i><i role="button" tabindex="0" class="van-hairline van-key van-key--gray van-key--delete">删除</i></div>
     </div>
   </div>
-  <div><button class="van-button van-button--primary van-button--normal"><span class="van-button__text">
+  <div><button class="van-button van-button--info van-button--normal"><span class="van-button__text">
       弹出自定义键盘
     </span></button>
     <div class="van-number-keyboard van-number-keyboard--custom van-number-keyboard--safe-area-inset-bottom" style="z-index: 100; display: none;" name="van-slide-up">